Computing system Lesson Objective:

Understand what is meant by a ‘computer system’

Learning Outcome:Define the key words and give a brief explanation for each.

Keywords: Input, output, storage, processing, DAC ADC, reliability, availability, MTBF, Hardware redundancy, RAID, disaster recovery.

What is a computer system? A computer system is made up of

hardware and software. Hardware is any physical component that makes up the computer. Software is any program that runs on the computer.

A computer system ...

ProcessInput Output

Storage

e.g. Keyboard, mouse

e.g. Monitor, speakers

e.g. Hard drive, RAM

???

Which has a computer system?Identify the input & output devices. What information is being processed?

Digital and Analogue (Real World)

Digital data is stored as 0’s and 1’s

Digital information occurs in steps

Analogue information makes gradual changes

Analogue data can be stored as writing, sound, …etc.

Digital to Analogue Converter

Digital and Analogue signals

ComputerNo entry to Analogue

Analogue Signals

Analogue SignalsAnalogue

to Digital Converter

DIGITAL ONLY!

Input Output

Reliability Many computer systems need a high

degree of reliability.For example:

Protecting against failures Redundancy

Disaster recovery

Redundancy Redundancy means having more than

one device in case of breakdown.

Redundancy Example RAID storage

RAID: http://www.youtube.com/watch?v=eE7Bfw9lFfs

Disaster recovery Some companies fully rely on computer

systems (e.g. web commerce)

They have plans for what to do if major systems fail

Companies often have their own procedures or they employ other companies who can do it.

Example of disaster recovery: